METHOD OF DETERMINING A TIMING OFFSET BETWEEN A FIRST CLOCK AND A SECOND CLOCK IN A COMMUNICATIONS NETWORK

• US 20060126437A1
• Filed: 10/20/2003
• Published: 06/15/2006
• Est. Priority Date: 10/25/2002
• Status: Active Grant

• Current Assignee: Unify GmbH & Co. KG (Atos SE)
• Original Assignee: Siemens AG
• Inventors: Smith, James David
• Granted Patent: US 7,120,090 B2
• Time in Patent Office: Days
• US Class Current: 368/46
• CPC Class Codes: H04J 3/0667 Bidirectional timestamps, e.g. NTP or PTP for compensation of clock drift and for compensation of propagation delays arrangements for monitoring round trip delays in packet switching networks H04L43/0864

Abstract

A system for determining a timing offset between a first clock and a second clock at respective first and second points in a communications network. A series of request signals is transmitted from the first point in the network to the second point in the network. A series of reply signals is transmitted from the second point in the network to the first point in the network. Each reply signal and a corresponding reply signal having a minimum round trip delay time are identified and a minimum single leg delay time is determined from the minimum round trip delay time. A timing offset between the clock values of the first clock and the second clock at a first instance is estimated, the estimation being based upon the minimum single leg delay time, and a transmission time and a reception time of one of the identified request signal and the corresponding reply signal, as given by the respective clocks at the transmission and reception points of the signal.

Claims